Elastic fluid turbine



June 20, 1939. LYSHOLM. I 2,162,957

ELASTIC FLUID TURBINE Filed Oct. 2, 1936 SSheets-Sheet 1' INEENTOR. BY V a June 20, 1939. A. LYSHOLM I ELASTIC FLUID TURBINE 3 Sheets-Sheet 2 Filed 001:. 2. 1936 June 20, 1939.

A. LYSHOLM ELAST IC FLUID TURBINE Filed Oct. 2, 1936 3 Sheets-Shegat 3 RQS /% iENTOR.

Patented June" 20, 1939 Um'reo stares 2,162,951 nms'rrc FLUID rename Application October 2', 193%, Serial No. 103,633

. In Germany October 3, 1935 14 Claims.

The present invention relates to.elastic fluid turbines and has particular reference to elastic fluid turbines of the radial flow type. Still more particularly the invention relates to radial flow turbines of the type in which a radial flow blade system has combined therewith an axial flow blade system for further expanding at the exhaust end of the turbine the motive fluid which has been partially expanded in the radial flow blade system. For convenience, such turbines may be termed radial-axial flow turbines.

Among the principal objects of the invention are to provide improved radial-axial turbine construction enabling such turbines to produce a larger power output for a given size of radial flow inlet for motive fluid than has heretofore been possible, to provide improved radial-axial flow turbine construction, which permits the attainment of higher efficiencies in large capacity turbines than has heretofore been obtainable, and to provide improved features of construction, whereby the blading of the axial flow system may more be derived from its use, may best be understood from a consideration of the ensuing portion of this specification in which is described by way of illustration, various embodiments of apparatus for carrying the invention into efiect.

In the drawings, forming a part of this specification:

Fig. 1 is a central longitudinal half section illustrating a turbine blade system embodying the invention;

Fig. 1a is a fragmentary section, on an enlarged scale, on the line I--I of Fig 1;

Fig. 2 is a'section similar to Fig. 1 illustrating,

a different form of blade system embodying the invention, the figure being broken to omit the inner portion of the radial flow blade system;

1 Fig. 3 is a section similar to Fig. 2, showing still another form of construction embodying the invention;

Fig. 4 is a section similar to Fig. 2 illustrating still another form of construction embodying the invention;

Fig. 5 is a fragmentary longitudinal section showing blading embodying one of the features of the invention; and

Fig. 6 is a section similar to Fig. 5 illustrating another arrangement of blading embodying the feature of the invention shown in Fig. 5.

Referring now more particularly to Fig. 1, the

-turbine illustrated is of the double rotation radial-axial flow type, provided with shafts2 and 4 adapted to rotate in opposite directions, Shafts 2 and 4 carry rotors 6 and B respectively, which rotors are of built-up construction. The main component parts of these rotors consist of the inner discs ill and I2 respectively, which are fixed to the turbine shafts and which carry the outer discs l4 and I6 respectively, the latter be- .ing attached to the inner discs by means of the radial pins l8 and 20. Rotor B carries a labyrinth ries of blade rings indicated generally at 34 and consisting of axially spaced ring bonds 36 between which the radial flow blades 38 are fixed. Alternate blade rings are attached to the same rotor with the intervening alternate rings attached to the opposite rotor, so that the radial flow blade rings are axially interleaved, adja: cent blade rings rotating in opposite directions.

Invthe embodiment illustrated, the last radial flow blade ring 34a is carried by means of radial pins 40 by the outer disc it of the rotor 8. The ring bonds 36a of this last radial flow blade ring, to which are attached the last row of radial flow blades 35a, also carry radially extending rings or flanges 42, to which are attached axial flow blade rows 44.

, Between the axial flow blade rows 44 'and the last ring of radial flow blades 34a, rows of stationary guide blades 46 are interposed, these latter blades being carried by the main stationary outer structure 48 through suitable intermediate members 50.

Each of the outer rotor discs I 4 and It carries -two rows of axial flow blades indicated generally at 52 and 54, the rows 52 being made up ofinner blades 56 attached to the rotor discs and outer blades 58 attached to members 60. carried by the outer ends of the blades 56. The blade rows 54 likewise are made up of inner blades 62 and outer blades 64, the inner blades beingthe outer axial flow blades 56 and 64.

stationary guide blades I6 are interposed between The stationary guide blades 16 are carried by the outer structure 48 and at their inner ends are attached to intermediate members I2, which serve to support'inner stationary guide blades 14 interposed between the inner axial flow blades 56 and 62.

For reasons which will be explained later, a

ring of stationary guide blades 16 carried by the.

right hand intermediate stationary member 56 is interposed between the rows of axial flow blades 44 and 56 carried by the right hand rotor I, there being no corresponding stationary blades in front of the axial flow blades 56 carried: by the left hand rotor 6.

The operation ofv the turbine is as follows: Motive fluid is admitted through the passages 16 to the inlet of the radial flow blade system, through which it flows outwardly in radial direction past the oppositely rotating rings. of

ary blades 46, I6 and 14. In this connection it is. to be noted that all of the blades in the right hand rows 46, 56 and 62 rotate in the same direction and in'the same direction as the outer ring 34a of radial flow blades- Consequently, stationary guide blades are. interposed between successive rows of this group.

The motive fluid flowing to the left in the radially inner stream from the chamber 80 also and 14. From the drawings it will be evident that while the left hand row of blades 44 rotates in the same direction as the last ring'of radial flow blades 35a, thus making the intermediate sta- "tionary guide blade 46 desirable, the blades 44 rotate oppositely with respect to the adjacent blades 56 which are attached to the rotor disc l4. Consequently no row of stationary guide blades corresponding to the blades 16 in the right side of the turbine are required between the blades 44 and 56 in the left side of the turbine.

Since blades 56 and 62 carried by the disc l4 rotate in the same direction, guide blades 14 are employed between these two'rows in the left side of the turbine as well as in the right side.

In the radially outer paths of flow for the motive fluid from chamber 80, the flow is through two stages of expansion at each side of the turbine, provided by the moving blades 58 and 64 and the stationary guide blades 68 and 10.

Considering the advantages that may be obtained from the above described construction it will be evident that the blades carried directly by the rotor discsS and 8 provide a multiple stage axial flow expansion system which provides for at least two steps of expansion for all of the steam exhausted from the radial flow system.

Because of the relatively large diameters of these blade rows and the relatively high peripheral speed a serious problem is presented in proflow blades constituting the exhaust. end of the system. These mechanical difllculties have established previous proposals for providing a greater number than two rows of axial flow blading as being impractical and attempts to enlarge the capacity of a given size of turbine by enlarging the radial flow blade system have also proved impractical from a structural standpoint because of the fact that the length of the radial flow blades as at present constructed is substantially maximum with present known methods of construction.

In accordance with the present invention the maximum practical number of axial flow expan-' sion stages heretofore available is increased and is increased by means of structural features which are entirely practical in large turbines of the kind 'where the large volumes of relatively low pressure motive fluid make a relatively large number ofaxial flow expansion stages desirable. By means of this invention a turbine of former construction and of 40,000 kw. capacity may be increased in capacity up to around 55,000 kw. by the auxiliary axial flow blades. In the form in which the auxiliary axial flow blades are employed they are relatively short and light and not only do they enable capacity to be increased but they also aid in increasing efficiency for a given size turbine, since as compared with previous forms they increase the Parsons figure for the turbine and further permit the last stages of the radial flow system to be constructed with-shorter and more eflicient blades than would otherwise be the case.

In the embodiment illustrated in Fig. 1 itwill 'be noted that the auxiliary axial flow blades 44 are. carried by the axial outer portions of the ring bonds 36a and the centrifugal-forces developed by the rotation of these blades and indicated by the arrows 82 develop turning moments tending to' twist these ring bonds. These forces tend to twist the right hand ring bond in counterclockwise direction in the plane of the figure and tend to twist the left hand ring bond clockwise in the plane of the figure.

As will be seen from Fig. 1a, the laterally extending projections of the ring bonds 36a are slotted at 36b so that the centrifugal forces developed in the projections are not absorbed by tension in the projections themselves and consequently produce bending moments on the main mass of the ring bonds.

The blades 35a which are attached to the axial inner sides of the ring bonds 36a exert centrifugal forces indicated by the arrow 64 which produce turning-moments acting on the ring bonds in opposition to the turning moments developed. by

the forces represented by arrows 82.

The opposed turning moments balance or substantially balance each other and reduce the stresses to which the ring bonds, the blades and.

the joints therebetween are subjected.

The counterbalancing or partial counterbalancing of forces of the kind indicated by arrow 84 has heretofore been proposed by utilization of masses forming a part of or attached to the outer portions of the ring bonds but heretofore such masses have had no other utility. By means of the present construction, the auxiliary axial flow blading not only improves the turbine construction from the standpoint of capacity and efficiency, but also accomplishes the additional function of providing counterbalanoing for twistting stresses set up in the radial flow ring bonds by the centrifugal forces developed by the radial flow blades.

The various features of the invention may-be carried into effect in forms of structure, differing from those illustrated in Fig. 1 and some examples of different structure are illustratedin the remaining figures which will now be-described. In the construction shown in Fig. 2 the general arrangement of blading is similar to that previously described, corresponding parts having the same reference numerals.

In this form'of construction, however, auxiliary axial flow blades 44 are carried by separate rings 85 attached to the outer turbine discs I4 and I6 by resilient connecting rings 88-which render the auxiliary blades expansively independent of the turbine discs. The rings 85 have sufiicient strength to absorb the centrifugal forces developed by the comparatively short and light blades 44 and the construction adds no additional tension stress to the discs, I4

and I8 which already are subjected to severe tension stresses by the relatively large centrifugal .forces developed bythe main axial flow blades.

The modification shown in Fig. 3 is'similar to that shown in Fig.2 but differs therefrom in that the rings,85a carrying the auxiliaryaxial'fiow blades 44 are attachedby means of radial pins 88 to the ring bonds 36a of the last radial flow blade ring. Pins 88 permit relative expansion 4Q movement between these rings and the rings 85a absorb the centrifugal stresses developed by blades 44 so that these stresses need not be carried by the ring bonds 36a. In this embodiment it will be noted that the pins 88 are mounted in axially extending projections 90 which may serve to produce turning moments counter to the turning moments produced by the blades a. Projecti'ohs 92, by means of which the right hand ring bond 36a is attached to disc I6, may also produce such counter turning moments. ment illustrated, additional, stationary guide blades 16a are provided to providesymmetry of structure although these blades are not essential since a double rotationefiect in the axial flow blade system is obtained in this construction between blades 44 and 56, as in the form of construction illustrated in Fig. 1.

In'Flg. 4 the construction is generally similar to that previously described except that the auxiliary blades 44 are carried by the inner rotor discs I0 and I2 which carry the radial flow blading.

In the specific embodiment shown blades 44 are carried directly by the two inner discs but it will be evident that in this form of construction theinner discs may carry the blades 44 indirectly through the medium of resilient connecting rings such as shown at. 86 in Fig. 2, or radial pins such as shown at 88 in 'Fig. 3.

In this modification it will be noted that while the axial flow blades 44 and 50 at the right of the turbine rotate in the saine direction as the last row of radial flow blades 34a, the axial flow blades 44 and 58 at the left of the turbine rotate oppositely with respect to the radial flow blades In the embodi 34a. Consequently if desiredthe left hand .row of stationary guideblades .46 maybe with'this'form ofconstruction.

It will be apparent that in order to admire advantages of counterbalancing the turning or twisting moments imposed on the radial flow ring bonds by the radial flow blades, through the medium of counter moments developed by the auxiliary axial'flow blades, the specific arrangement of suchblades as shown in Fig. 1 need not necessarily be employed and itwillfurther 'be evidentthat this cidunterbalancing' use of axial flow blades may be employed in turbines in which the axial flow blade system as a whole is different from that shown in Fig, 1'.

In order to illustrate different forms of appli cation of this particular feature of the invention,,I have illustrated'different embodiinents xin Figs. 5 and 6 by way of illustration! "Referring now more particularly to thesefigures, Fig. 5 illustrates asomewhat simplified form of turbine in whichithe turbine discs 14a and. Mia carry single rows of axial flow blades 94 and-'96 respectively. a .Y

'The outer radial flow blade ring I00, comprising blades I02 fixed between ring bonds I04 and I06, carries a row of axial flow blades I08. fixed to the ring bond I04 and a similar row H0 fixed to the ring bond I06. Since in this embodiment the blade ring I00 is attached to and rotates with the disc lIia, the blades 96 and IIO rotate in the same direction, and consequently a stationary ,guide blade row II2 is interposed between these The blade rows 94 -sidered as continuations of blades I02 since all rotate in the same direction and no intervening stationary guide bladesare employed.

rows I08 and I I0 are indicated as constituting the entire axial flow moving blade system. Here again the blades carried by the ring bonds I04 and I06 constitute a symmetrical system but as contrasted with the embodiment shown in Fig. 5, stationary guide blade rows I I4 and I I8 are interposed between the axial flow rows I08 and I I0, respectively, and radial flow blades I02.

It will be understood that in all of the various embodiments illustrated, in order to secure the benefits of the feature of the invention involving balancing of turning moments, the axial flow blade rows that are attached to the ring bonds of the radial flow ring, are attached so thatthe forces exerted thereby are applied on the sides of the centers of gravity of the ring bonds opposite the sides where the blades are attached. In the forms of construction illustrated it may be said that the axial flow blades are attached axially outside the centers of'g'ravity, the places of'attachment of the radial flow blades being axially inside such centers.

exhaust losses in a turbine through their guiding action on the motive fluid exhausted from the radial flow blade system.

From the foregoing it will be evident that many changes and variations in the speciflc forms of apparatus herein illustrated by way of example may be made without departing from the invention, the scope of which is to be understood as including all forms of construction falling within the terms of the appended claims when construed as broadly as is consistent with the state of the prior art.

What I claim is:

1. In an elastic fluid turbine, a radial flow blade system and an axial flow blade system for expanding motive fluid exhaustedby said radial flow system, said axial flow blade system including blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted by said radial flow system for further expansion in the turbine and auxiliary axial flow blades providing an additional stage of expansion for a portion of said motive fluid, said auxiliary axial flow blades being arranged in the path of flow of the motive fluid toaprovide a preliminary stage for expanding a portion of said fluid before it is expanded in the remaining stages of axial flow blading and said auxiliary .stage being mounted to have radial movement due to expansion and contraction independently of said remaining stages of axial flow blading.

2. In an elastic fluid turbine, a radial flow blade system, an axial flow blade system for expanding motive fluid exhausted by said radial flow system.

said axial flow blade system including a plurality of rows of main axial flow rotor blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted by said radial flow'system for further expansion in the turbine and auxiliary axial flow rotor blades providing an additional stage of expansion for a portion of said motive fluid, and means for dividing the motive fluid passing through said axial flow system into radially separated inner and outer streams, said auxiliary axial flow blades being ar ranged to expand only that portion of the motive fluid flowing through a radially inner stream and to provide the first axial flow expansion stage for such inner stream portion and said additional stage being mounted to have radial movement due to expansion and contraction independently of the remaining stages of axial flow blading.

3. In an elastic fluid turbine, a radial flow blade system and an axial flow blade system for expanding motive fluid exhausted by said radial flow systern. said axial flow blade system including blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted by said radial flow system for further expansion in the turbine and auxiliary axial flow blades providing an additional stage of expansion for a portion of said motive fluid, said auxiliary axial flow blades being carried by the last blade ring of said radial flow system.

4. In an elastic fluid turbine, a radial flow blade system, an axial flow blade system for expanding motive fluid exhausted by said radial flow system, said axial flow blade systemincluding a plurality of rows of main axial flow blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted by said radial flow system for further expansion in the turbine and auxiliary axial flow blades providing an additional stage of expansion for a portion of said motive fluid, rotor discs for carrying said main axial flow blades,.and rings expansible independently 01' said rotor discs for carrying said auxiliary axial flow blades.

5. In an elastic fluid turbine, a radial flow blade system, an axial flow blade system for expanding motive fluid exhausted by said radial flow system, said axial flow blade system including a plurality of rows 01' main axial flow blades providing a plurality of serially arranged stages of expansion for all oi. the motive fluid exhausted by said radial flow system for further expansion in the turbine and auxiliary axial flow blades providing an additional stage 01- expansion for a portion of said motive fluid, rotor discs for carrying said main axial flow blades, and rotor discs expansible independently of the first mentioned rotor discs for carrying said radial flow blades. the secondmentioned rotor discs carrying said auxiliary axial flow blades.

6. In an elastic fluid turbine, a radial flow blade system, an axial flow blade system for expanding motive fluid exhausted. by said radial flow system, said axial flow blade system including a plurality of rows of main axialflow blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted by said radial flow system for further expension in the turbine and auxiliary axial flow blades providing an additional stage of expansion for a portion of said motive fluid, and means for dividing the motive fluid passing through said axial flow system into radially separated inner and outer streams, said rows of main axial flow blades being divided into rings of radially separate inner and outer blades and said auxiliary axial flow blades being arranged to expand only that portion of the motive fluid flowing to the radially inner of said rings of main axial flow blades. v

'7. In an elastic fluid turbine, a radial flow blade system and an axial flow blade system for expanding motive fluid exhausted from said radial flow system, said axial flow blade system comprising blades providing a plurality of serially arranged stages of expansion for all of the motive fluid exhausted from said radial flow system for further expansion in the turbine and auxiliary axial flow blades providing an additional stage of expansion for a portion of said motive fluid, said radial flow blade system including a last blade row consisting of axially spaced ring bonds and blades fixed to the axially inner sides ofsaid ring bonds and said auxiliary axial flow blades being carried by the axially outer parts of said ring bonds, whereby to provide mass producing turning moments on said ring bonds acting counter to the turning moments produced on the ring bonds by the radial 8. In an elastic fluid turbine, a radial flow blade system including a blade ring consisting of axially spaced ring bonds and blades flxed therebetween, said ring bonds including counterbalancing mass located axially outside the centers of gravity of the ring bonds and said mass being constituted at least in part by axial flow blades.

9. In an elastic fluid turbine, a radial flow blade system including a blade' ring consisting of axially spaced ring bonds and blades fixed therebetween, each of said ring bonds having a row of axial flow blades fixed thereto axially outside the center of gravity of the ring bond.

.10. In a double rotation elastic fluid turbine, oppositely rotating rotor structures each carrying main axial flow blades, a radial flow blade of auxiliary axial flow blades attached to eachof said ring bonds axially outside the center of gravity thereof, one of said rows of auxiliary axialflow bladesexhausting directly to arow' of moving main axial flow blades rotating in opposite direction and a row of stationary guide blades to which the other of said rows of auxiliary guide blades exhausts, said row of stationary guide blades being arranged in front of a row of main axial flow blades rotating in the same direction as said rows of auxiliary axial flowblades.

11. In an elastic fluid turbine, a radial flow blade ring comprising axially spaced ring bonds with radialflow blades fixed therebetween, projections extending from the axially outer sides of said rings, a row of axial flow blades, a ring member for carrying said-axial flow blades, and attaching means for carrying said ring member from the projections on one of said ring bonds.

12. In an elastic fluid turbine a radial flow blade system, an axial flow blade system comprising axial flow blades to each side of the radial flow system, said radial flow system including a blade ring having axially spaced ring bonds and radial flow blades fixed therebetween, and axial flow blades attached to each of said ring bonds, the last mentioned axial flow blades being arranged in front of the first mentioned axial flow blades and receiving motive fluid directly from said radial flow blades.

13. In an elastic fluid turbine, a radial flow blade ring including a ring bond having radial fiow blades attached to one side of the center of gravity thereof and axial flow blades attached.

to the other side of the center of gravity thereof to produce moments acting counter to the momen-ts produced by'said radial flow blades, said axial flow blades being arranged to receive motive fluid directly from said radial flow blades.

14. In an elastic fluid turbine, a radial flow blade ring including axially spaced ring bonds having radial flow blade rings attached to their ends to the axially inner sides of the centers of gravity of said ring bonds, and means for counter balancing the twisting forces imposed on said ring bonds by said radial flow blades comprising a series of projections extending from one of said ring bonds axially outside the center of gravity thereof and a row of axial flow blades attached to the other of said ring bonds axially outside of its center of gravity.

ALF LYSHOLM. 

